<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<div id="">

		</div>
	</body>

</html>
<style type="text/css">
	div {
		width: 200px;
		height: 200px;
		border: 1px solid black;
		/* 给左上角和右下角添加10px圆角,给右上角和左下角添加50%的圆角*/
		
	}
</style>